The
Rhyacian Period ( /raɪˈeɪsiən/; Greek: ῥύαξ,
translit. rhýax, meaning "stream of lava") is the second
geologic period in the
Paleoproterozoic Era and lasted from 2300 Mya
to 2050 Mya (million years ago).[1] Instead of being based on
stratigraphy, these dates are defined chronometrically.[2]
The
Bushveld Igneous ComplexBushveld Igneous Complex and other similar intrusions formed
during this period.[2]
The Huronian (Makganyene) global glaciation began at the start of the
Rhyacian lasted 100 million years.[3]
The first known eukaryotes began to evolve in the
Rhyacian period. The
multicellular Francevillian Group Fossils, at 2.1-Gyr are from the
Rhyacian period.[4]
For the time period from 2250 Ma to 2060 Ma, an alternative period
based on stratigraphy rather than chronometry, named either the
Jatulian or the Eukaryian, was suggested in the geological timescale
review 2012 edited by Gradstein et al.,[5] but as of
February 2017[update], this has not yet been officially adopted
by the IUGS. The term Jatulian is, however, used in the regional
stratigraphy of the
Paleoproterozoic rocks of Fennoscandia.[6]
References[edit]